Some information is not accessible by our 5 senses, it is then the sixth sense that goes into action with the help of imagination. When have extrasensory perceptions, the brain generates signals to issue the information for us in an understandable form, according to our knowledge, our abilities, our preferences...
Our imagination can for instance generate colors to represent to us the state of a person, just like a mapping software would do with the earth. When we see the earth painted in red, orange or green on a screen or on a map, are these colors are really present on the globe where it is shown? No. Is it a confabulation? No. It is a graphical representation with arbitrary colors conventions. Red indicates high altitudes or high temperatures, green shows that the altitude or the temperature is low.
Similarly, perceiving colors around an animate or inanimate being doesn't necessarily means that it/he/she emits light. This doesn't mean that we have hallucinations either. It is rather about synthetic images generated by the brain to represent an information that is beyond our 5 senses. The same information could have been represented in with sound, smell, impression, feeling, thought, tactile sensation, visual flash, word, music... It depends on the external conditions and operation mode of the perceiver.
Extrasensory perception in the form of light is beautiful but it raises the problem of interpretation. The meaning we give to colors depends entirely on our cultural conditioning. The colors don't have the same meaning from one country to another, that which brings happiness and prosperity here is considered as a sign of misfortune over there. In general we believe that blue is cold while red is hot and yet from a purely physical point of view, it is exactly the opposite. When an object is heated, it turns red and gradually moves towards blue as the temperature increases. There is no universal meaning to the colors, it depends on the experience and knowledge of each and everyone.
Extrasensory perception in the form of light also raises the problem of the loss of information. To perceive, we must first capture extrasensory signals. Our sensors have their limits so the raw data is truncated by our physical, mental and emotional abilities. Then comes the conversion of the incoming signals. Our imagination generates colors based on the conventions that we have learned. Signals that don't match any of our conventions are discarded. This translation truncates the information a second time. Finally, we interpret the generated colors to make sense and to understand the original message. The information is truncated a third time.
It is best to issue extrasensory perception by involving all the senses, rather than being limited to one sensory channel. Insofar as our limitations and interpretations filter information, it is better to have an imagination flexible enough to generate the 5 types of sensations that our senses recognize. Working on the perception of sounds can help acquire this flexibility because the sounds are more complex than images and less subject to cultural conditioning.